Evacuated insulation elements include a pressure-resistant, open-pore core having low thermal conductivity, as well as a completely enclosed covering made of a film, preferably a plastic film, which has a high barrier effect against gases and water vapor. The core is evacuated, generally to a gas pressure between 0.01 mbar and 5 mbar. As a result, the thermal conductivity of the residual gas within the porous core is reduced to a minimum. Depending on the core material, the thermal conductivity in the evacuated state is between 0.0015 and 0.010 W/mK. Common core materials are powders, open-pore foams, glass fibers, or aerogels. Foams, glass fibers, or powders are usually present in the form of a panel which is cut to the desired size, enclosed with a high-barrier film, and pumped free of air in a vacuum chamber.
A structure having an inner core and a shell enclosing same which is separated from the inner core by an inner film is described in WO 03/002828 A1.
A high-barrier film which is used may be made up of multiple film layers, composed of polyester and polyethylene, for example, laminated one on top of the other, whereby individual layers may additionally be vapor-deposited with a metallic layer to achieve a high diffusion barrier against the penetration of gases and water vapor. However, it has been found that a high-barrier film generally cannot be used to the same extent as a barrier against all types of gases or vapors; rather, it blocks certain types of gas or vapor better than others. A major problem which has not been solved thus far is the simultaneous blocking of air and its gaseous constituents such as oxygen, nitrogen, etc. on the one hand, and blocking of water vapor on the other hand.
The disadvantages of the described prior art have resulted in the task, initiated by the invention, of refining a generic vacuum insulation element in such a way that it is equally resistant to all types of gas and vapor relevant in practice, i.e., it reliably prevents penetration of same.